i found a book I need in the catalog but it is checked out, can i put a hold on it? how?
Yes, you can place a hold on items that are currently checked out.
If you are searching the catalog using COMCAT, if the title you are interested in show a status of not available/checked out. Expand the page by clicking on the title.
To the right of the page you will see
Click on place hold, log into COMCAT using your COM ID and Last name, click on Hold. When the item becomes available you will be notified either by email, phone, or mail.